php教程

PDO 类

(PHP 5 >= 5.1.0, PHP 7, PECL pdo >= 0.1.0)

简介

代表 PHP 和数据库服务之间的一个连接

类摘要

PDO {
__construct ( string $dsn [, string $username [, string $password [, array $driver_options ]]] )
beginTransaction ( void ) : bool
commit ( void ) : bool
errorCode ( void ) : mixed
public errorInfo ( void ) : array
exec ( string $statement ) : int
getAttribute ( int $attribute ) : mixed
static getAvailableDrivers ( void ) : array
inTransaction ( void ) : bool
lastInsertId ([ string $name = NULL ] ) : string
public prepare ( string $statement [, array $driver_options = array() ] ) : PDOStatement
public query ( string $statement ) : PDOStatement
public quote ( string $string [, int $parameter_type = PDO::PARAM_STR ] ) : string
rollBack ( void ) : bool
setAttribute ( int $attribute , mixed $value ) : bool
}

Table of Contents

User Contributed Notes

Ale L 01-Nov-2018 06:17
1) Do not use your ddbb info in the same file

AND

2) DO NOT NEVER USE "All privileges user" for everything, always create an alternative user with restricted permissions (basic: SELECT, INSERT and so on)
ronakjain2012 at gmail dot com 25-Feb-2018 12:12
<?php

class Database
{
    private static
$_instance;
    private
$_connection;
    private
$DB_host = "localhost";
    private
$DB_user_name = "root";
    private
$DB_user_password = "";
    private
$DB_driver = "mysql";
    private
$DB_database = "test";
    public static function
init()
    {
        try {
            if (
is_null(self::$_instance) || empty(self::$_instance)) {
               
self::$_instance = new self();
                return
self::$_instance;
            }else{
                return
self::$_instance;
            }
        } catch (
Exception $e) {
            return
self::class;
        }
    }

    function
__construct()
    {
        try {
            if (
is_null($this->_connection) || empty($this->_connection)) {
               
$this->_connection = new \PDO($this->DB_driver.':host='.$this->DB_host.';dbname='.$this->DB_database, $this->DB_user_name, $this->DB_user_password);
            }
        } catch (
Exception $e) {
           
$this->_connection = $e;
        }
    }

    public function
connect()
    {
        return
$this->_connection ? $this->_connection : null;
    }
}
sinri at everstray dot com 07-Dec-2017 03:38
For some Database Environment, such as Aliyun DRDS (Distributed Relational Database Service), cannot process preparing for SQL.
For such cases, the option `\PDO::ATTR_EMULATE_PREPARES` should be set to true. If you always got reports about "Failed to prepare SQL" while this option were set to false, you might try to turn on this option to emulate prepares for SQL.
Anonymous 30-Aug-2017 08:05
I personnaly create a new instance of PDO like this :

$dbDatas = parse_ini_file( DB_FILE );
 $dbOptions = [
 \PDO::ATTR_DEFAULT_FECTH_MODE => \PDO::FETCH_OBJ,
 \PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
 ];

 $dsn = sprintf( 'mysql:dbname=%s;host=%s', $dbDatas['dbname'],
$dbDatas['host'] );
 
 $this->cn = new \PDO( $dsn, $dbDatas['user'], $dbDatas['password'],
$dbOptions );
 $this->cn->exec( 'SET CHARACTER SET UTF8' );
sideshowAnthony at googlemail dot com 23-Jul-2015 11:54
Here is a cheeky PDO helper class to get you started . . .

define('DB_MAIN', 'localhost|user1|pa55word|db1');

// Connect to database db1
$db = new my_db(DB_MAIN);

// Request "SELECT * FROM table1 WHERE a=16 AND b=22"
// Get an array of stdClass's
$rows = $db->fetchAll('SELECT * FROM table1 WHERE a=? AND b=?', 16, 22);

class my_db{

    private static $databases;
    private $connection;

    public function __construct($connDetails){
        if(!is_object(self::$databases[$connDetails])){
            list($host, $user, $pass, $dbname) = explode('|', $connDetails);
            $dsn = "mysql:host=$host;dbname=$dbname";
            self::$databases[$connDetails] = new PDO($dsn, $user, $pass);
        }
        $this->connection = self::$databases[$connDetails];
    }
   
    public function fetchAll($sql){
        $args = func_get_args();
        array_shift($args);
        $statement = $this->connection->prepare($sql);       
        $statement->execute($args);
         return $statement->fetchAll(PDO::FETCH_OBJ);
    }
}
rumsg at mail dot ru 05-May-2015 12:33
$DB = new PDO('mysql:host=127.0.0.1;port=3306;dbname=anexis_new;charset=UTF8;','root','password', array(PDO::ATTR_PERSISTENT=>true));
$DB->query("SET NAMES utf8;");
thz at plista dot com 14-Jun-2013 01:25
Starting with PHP 5.4 you are unable to use persistent connections when you have your own database class derived from the native PDO class. If your code uses this combination, you will encounter segmentation faults during the cleanup of the PHP process.
You can still use _either_ a derived PDO class _or_ persistent connections.

For more information, please see this bug report: https://bugs.php.net/bug.php?id=63176
williambarry007 at gmail dot com 12-Oct-2011 01:10
PDO and Dependency Injection

Dependency injection is good for testing.  But for anyone wanting various data mapper objects to have a database connection, dependency injection can make other model code very messy because database objects have to be instantiated all over the place and given to the data mapper objects.

The code below is a good way to maintain dependency injection while keeping clean and minimal model code.

<?php

class DataMapper
{
    public static
$db;
   
    public static function
init($db)
    {
       
self::$db = $db;
    }
}

class
VendorMapper extends DataMapper
{
    public static function
add($vendor)
    {
       
$st = self::$db->prepare(
           
"insert into vendors set
            first_name = :first_name,
            last_name = :last_name"
       
);
       
$st->execute(array(
           
':first_name' => $vendor->first_name,
           
':last_name' => $vendor->last_name
       
));
    }
}

// In your bootstrap
$db = new PDO(...);
DataMapper::init($db);

// In your model logic
$vendor = new Vendor('John', 'Doe');
VendorMapper::add($vendor);

?>
kcleung at kcleung dot no-ip dot org 02-May-2010 03:47
Here is an singleton PDO example:

###### config.ini ######
db_driver=mysql
db_user=root
db_password=924892xp

[dsn]
host=localhost
port=3306
dbname=localhost

[db_options]
PDO::MYSQL_ATTR_INIT_COMMAND=set names utf8

[db_attributes]
ATTR_ERRMODE=ERRMODE_EXCEPTION
############

<?php class Database {
    private static
$link = null ;

    private static function
getLink ( ) {
        if (
self :: $link ) {
            return
self :: $link ;
        }

       
$ini = _BASE_DIR . "config.ini" ;
       
$parse = parse_ini_file ( $ini , true ) ;

       
$driver = $parse [ "db_driver" ] ;
       
$dsn = "${driver}:" ;
       
$user = $parse [ "db_user" ] ;
       
$password = $parse [ "db_password" ] ;
       
$options = $parse [ "db_options" ] ;
       
$attributes = $parse [ "db_attributes" ] ;

        foreach (
$parse [ "dsn" ] as $k => $v ) {
           
$dsn .= "${k}=${v};" ;
        }

       
self :: $link = new PDO ( $dsn, $user, $password, $options ) ;

        foreach (
$attributes as $k => $v ) {
           
self :: $link -> setAttribute ( constant ( "PDO::{$k}" )
                ,
constant ( "PDO::{$v}" ) ) ;
        }

        return
self :: $link ;
    }

    public static function
__callStatic ( $name, $args ) {
       
$callback = array ( self :: getLink ( ), $name ) ;
        return
call_user_func_array ( $callback , $args ) ;
    }
}
?>

<?php // examples
$stmt = Database :: prepare ( "SELECT 'something' ;" ) ;
$stmt -> execute ( ) ;
var_dump ( $stmt -> fetchAll ( ) ) ;
$stmt -> closeCursor ( ) ;
?>
Megaloman 18-Feb-2009 07:03
"And storing username/password inside class is not a very good idea for production code."

Good idea is to store database connection settings in *.ini files but you have to restrict access to them. For example this way:

my_setting.ini:
[database]
driver = mysql
host = localhost
;port = 3306
schema = db_schema
username = user
password = secret

Database connection:
<?php
class MyPDO extends PDO
{
    public function
__construct($file = 'my_setting.ini')
    {
        if (!
$settings = parse_ini_file($file, TRUE)) throw new exception('Unable to open ' . $file . '.');
       
       
$dns = $settings['database']['driver'] .
       
':host=' . $settings['database']['host'] .
        ((!empty(
$settings['database']['port'])) ? (';port=' . $settings['database']['port']) : '') .
       
';dbname=' . $settings['database']['schema'];
       
       
parent::__construct($dns, $settings['database']['username'], $settings['database']['password']);
    }
}
?>

Database connection parameters are accessible via human readable ini file for those who screams even if they see one PHP/HTML/any_other command.
anrdaemon at freemail dot ru 22-Aug-2008 01:16
Keep in mind, you MUST NOT use 'root' user in your applications, unless your application designed to do a database maintenance.

And storing username/password inside class is not a very good idea for production code. You would need to edit the actual working code to change settings, which is bad.
schizo_mind at hotmail dot com 28-Jul-2008 10:00
<?php
class PDOConfig extends PDO {
   
    private
$engine;
    private
$host;
    private
$database;
    private
$user;
    private
$pass;
   
    public function
__construct(){
       
$this->engine = 'mysql';
       
$this->host = 'localhost';
       
$this->database = '';
       
$this->user = 'root';
       
$this->pass = '';
       
$dns = $this->engine.':dbname='.$this->database.";host=".$this->host;
       
parent::__construct( $dns, $this->user, $this->pass );
    }
}
?>

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